const fs = require('fs');
const readline = require('readline');
const {google} = require('googleapis');

// If modifying these scopes, delete token.json.
const SCOPES = ['https://www.googleapis.com/auth/calendar'];
// The file token.json stores the user's access and refresh tokens, and is
// created automatically when the authorization flow completes for the first
// time.
const TOKEN_PATH = 'token.json';

// Load client secrets from a local file.
exports.apiCalendar=function(){
fs.readFile('credentials.json', (err, content) => {
  if (err) return console.log('Error loading client secret file:', err);
  // Authorize a client with credentials, then call the Google Calendar API.
  authorize(JSON.parse(content), listEvents);
  authorize(JSON.parse(content), addEvents);
});
}
/**
 * Create an OAuth2 client with the given credentials, and then execute the
 * given callback function.
 * @param {Object} credentials The authorization client credentials.
 * @param {function} callback The callback to call with the authorized client.
 */
function authorize(credentials, callback) {
  const {client_secret, client_id, redirect_uris} = credentials.installed;
  const oAuth2Client = new google.auth.OAuth2(
      client_id, client_secret, redirect_uris[0]);

  // Check if we have previously stored a token.
  fs.readFile(TOKEN_PATH, (err, token) => {
    if (err) return getAccessToken(oAuth2Client, callback);
    oAuth2Client.setCredentials(JSON.parse(token));
    callback(oAuth2Client);
  });
}

/**
 * Get and store new token after prompting for user authorization, and then
 * execute the given callback with the authorized OAuth2 client.
 * @param {google.auth.OAuth2} oAuth2Client The OAuth2 client to get token for.
 * @param {getEventsCallback} callback The callback for the authorized client.
 */
function getAccessToken(oAuth2Client, callback) {
  const authUrl = oAuth2Client.generateAuthUrl({
    access_type: 'offline',
    scope: SCOPES,
  });
  console.log('Authorize this app by visiting this url:', authUrl);
  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
  });
  rl.question('Enter the code from that page here: ', (code) => {
    rl.close();
    oAuth2Client.getToken(code, (err, token) => {
      if (err) return console.error('Error retrieving access token', err);
      oAuth2Client.setCredentials(token);
      // Store the token to disk for later program executions
      fs.writeFile(TOKEN_PATH, JSON.stringify(token), (err) => {
        if (err) return console.error(err);
        console.log('Token stored to', TOKEN_PATH);
      });
      callback(oAuth2Client);
    });
  });
}

/**
 * Lists the next 10 events on the user's primary calendar.
 * @param {google.auth.OAuth2} auth An authorized OAuth2 client.
 */
function listEvents(auth) {
  const calendar = google.calendar({version: 'v3', auth});
  calendar.events.list({
    calendarId: 'primary',
    timeMin: (new Date()).toISOString(),
    maxResults: 10,
    singleEvents: true,
    orderBy: 'startTime',
  }, (err, res) => {
    if (err) return console.log('The API returned an error: ' + err);
    const events = res.data.items;
    if (events.length) {
      console.log('Upcoming 10 events:');
      events.map((event, i) => {
        const start = event.start.dateTime || event.start.date;
        console.log(`${start} - ${event.summary}`);
      });
    } else {
      console.log('No upcoming events found.');
    }
  });
}

function addEvents(auth) {
  const calendar = google.calendar({version: 'v3', auth});
  
  calendar.events.insert({
    calendarId: 'primary',
    resource: event,
  }, function(err, event) {
    if (err) {
      console.log('There was an error contacting the Calendar service: ' + err);
      return;
    }
    console.log('Event created: %s', event.data.htmlLink);
  });
 calendar.events.insert({
    calendarId: 'primary',
    timeMin: (new Date()).toISOString(),
    maxResults: 10,
    singleEvents: true,
    orderBy: 'startTime',
  }, (err, res) => {
    if (err) return console.log('The API returned an error: ' + err);
    const events = res.data.items;
    if (events.length) {
      console.log('Upcoming 10 events:');
      events.map((event, i) => {
        const start = event.start.dateTime || event.start.date;
        console.log(`${start} - ${event.summary}`);
      });
    } else {
      console.log('No upcoming events found.');
    }
  });
}

// Refer to the Node.js quickstart on how to setup the environment:
// https://developers.google.com/calendar/quickstart/node
// Change the scope to 'https://www.googleapis.com/auth/calendar' and delete any
// stored credentials.

var event = {
  'summary': 'Göd trafó csere',
  'location': 'GÖD Samsung',
  'description': 'Transzformátor telepítése.',
  'start': {
    'date': '2021-05-10',
    'timeZone': 'America/Los_Angeles',
  },
  'end': {
    'date': '2021-05-14',
    'timeZone': 'America/Los_Angeles',
  },

  'attendees': [
    { 'email': 'klmuhely@gmail.com',
      'displayName': 'Kapusi Imre'},
    {'email': 'v.joszef@gmail.com',
    'displayName': 'Kiss Sándor'},
    {'email': 'kutafaja@hotmail.com',
    'displayName': 'Vincze József'},
  ],
  'reminders': {
    'useDefault': false,
    'overrides': [
      {'method': 'email', 'minutes': 24 * 60},
      {'method': 'popup', 'minutes': 4320},
    ],
  },
};